The picture below shows all the leftover parts from this project.
I got tired of the ETX finder scope pretty quickly. In the pile of leftover parts, I noticed the DS-60 right angle adapter. I took the ETX finder apart and glued its objective to one end of the right angle adapter. I put in a low power eyepiece from the DS-60 in the other end and presto! A new right angle finder. I had to enlarge the finder holder on the ETX slightly, but it works.
This was a quick project. It only took a couple of nights of leisurely work, and the resulting telescope is a big improvement over both the original ETX-90RA and DS-60EC. The overall project cost under $500 (including taxes, shipping and the Scopetronix eyepiece adapter for the rear Cassegrain focus). A little less than buying an ETX-90EC outright (and a lot more work), but I really enjoyed the project, and that's what matters.
Using the telescope, I've noticed that there's some slop in both axes. I don't think this is due to the Frankenstein nature of this telescope, but due to the way Meade has implemented their clutch system. The gear for each axis is free floating, held in place between two keyed but loose washers. You can push the washers (and gear) together by tightening the clutch, but this will always allow some slippage of the gear. Meade had a reason for this, especially in the DS-60; slewing too far in certain directions would cause the telescope's OTA to hit the base of the telescope, and could cause the motors to burn out, damage the gears or both.
My next change will probably be to lock the gear in place with two nuts and some Locktite. I'll add limit switches to the Dec axis to cut off power to the Dec motor if the limit switch is hit.
The apparently flimsy tripod from the DS-60 is surprisingly good. It could use some sort of stiffening in the legs, but so far, I haven't had any problems with it.
Frank Henriquez, November 16, 2002
Some links of interest:
Steve Bedair's DS Powered Telescope Mounts
Hans Peter Wallner's Computer Controlled Telescope Mounts
Mike Weasner's ETX site